title: In vitro toxicity of respirable-size particles of diatomaceous earth and crystalline silica compared with asbestos and titanium dioxide.
abstract: The relationship between particle characteristics and in vitro toxicity was investigated using Chinese hamster ovary cells. Test dusts included respirable natural (Nat) and flux-calcined (FC) diatomaceous earth (DE), quartz, cristobalite, TiO2, and chrysotile and crocidolite asbestos. All dusts elicited a qualitatively similar, concentration-dependent response: particle uptake, induction of micro- and polynuclei, and reduction in cell proliferation. However, similar mass concentrations of the dusts yielded a 35-fold range of toxicity: chrysotile > crocidolite > Nat DE > FC DE > quartz > Cristobalite > TiO2. In vitro toxicity did not correlate with crystalline silica content, surface area, composition, volume, particles/cm2, or fibrous geometry. Toxicity was closely associated with the number of particles/cm2 culture surface that had at least one dimension > 7.5 mu. Thus particle size but not shape could be a determinant of in vitro toxicity. Particle size might also impact in vivo pathogenesis.
authors.affiliation: Johns Manville Corporation Technical Center, Littleton, CO 80162-5005, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Hart
authors.forename: T W
authors.initials: TW
authors.lastname: Hesterberg
mesh_terms: D000818:Animals; D001194:Asbestos / Q000737:chemistry / Q000633:toxicity*; D016466:CHO Cells / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D006224:Cricetinae; D007692:Diatomaceous Earth / Q000737:chemistry / Q000633:toxicity*; D066298:In Vitro Techniques; D010316:Particle Size; D011791:Quartz / Q000737:chemistry / Q000633:toxicity*; D012822:Silicon Dioxide / Q000737:chemistry / Q000633:toxicity*; D014025:Titanium / Q000737:chemistry / Q000633:toxicity*
chemical_list: D001194:Asbestos; D011791:Quartz; D007692:Diatomaceous Earth; D012822:Silicon Dioxide; D014025:Titanium